Question

A crane operated by an electric motor has a mass of 500kg.it raises a load of 300 kg vertically at a steady speed 0. 2m/s. Assume resistance to be constants at the 1200N.what is the power required To raise. The load.

Answer 1

weight of the crane + weight of the load = 500 + 300 = 800 kg
gravitational force due to the weight = 800 * g =  800 * 10  Newtons.

     Resistance to lifting action of the crane  like friction etc. = 1,200 N
  Total force needed to lift the load with a velocity 0.2 m/s = 8,000 + 1,200 Newtons

power needed to lift the load with a velocity (uniform)
     P = F * v  =  9, 200 N * 0.2 m/sec =  1, 840 Watts